1. Field
Apparatuses and methods consistent with the present inventive concept relate to providing a server, a client device, a method for generating a transport stream thereof and for processing the transport stream thereof, and more particularly, providing a server which transmits scrambled broadcasting contents and processes them, a client device, a method for generating a transport stream thereof, and processing the transport stream thereof.
2. Description of the Related Art
In digital broadcasts, instead of relying on the existing advertising revenues, broadcasters attempt to create added value by providing high-quality broadcasting services to subscribers and subscription-based broadcasting services which collect a television subscription fee from the subscribers. Therefore, transmitted data of various multimedia is protected, and only subscribers who are authorized to receive the data can watch. To this end, the Conditional Access System (CAS) has been developed.
CAS introduces the concept of a subscriber to broadcasts, and enables only subscribers who have secured the right to watch to receive specific programs. CAS entails a series of processes in which each digital broadcast receiver determines whether a receiver can receive any specific broadcasting program. In general, an audio/video (A/V) stream is scrambled with Control Word (CW), and an Entitlement Control Message (ECM) and an Entitlement Management Message (EMM) which are used for encrypting CW are transmitted in a multiplex form on the transmission side of CAS, and ECM and EMM are decrypted by the use of a smart card to recover CW, and the scrambled A/V stream is descrambled on the receiving side of CAS.
In a conventional system, CAS keys required for descrambling ECM and EMM are embedded in a digital rights management (DRM) integrated circuit (IC) or other similar circuit, or the corresponding CAS key is embedded in advance in a storage medium such as, for example, an electrically erasable programmable read-only memory (EEPROM), when receiver manufacturers produce products.
Therefore, in a conventional system, if an embedded CAS key is damaged, scrambled digital broadcasts cannot be descrambled smoothly, because it is not possible to recover the corresponding CAS key on the receiving side, and this results in incurring a replacement cost for a receiving device such as, for example, a television provided to the receiving side. Further, if a CAS key is stolen by a third party, a problem arises that the CAS key cannot be updated from a transmission side to the receiving side.